wonder if that is why the vegetable gycerine works, it is a type of sweetner used in baing to keep icing softOil and water don't mix, so while adding oil might stave off freezing by altering the freezing point of the surface of the water, it won't alter the freezing point of the remaining body of water. Unless you have a large amount of water, the water will freeze, altering its density, and the ice will float to the top.
If you want to add oil, I would really suggest using a vegetable based oil instead of a petroleum product. Also, adding sugar to water will lower the freezing point and give additional calories, which are good for keeping warm.